Cyclocarya paliurus is a versatile tree species with immense potential for development, as it combines edible, medicinal, and ornamental functions. Low temperature is one of the important abiotic factors that affect plant survival and flourishing but their response mechanism to low temperature is not yet clear. In this study, we utilized annual shoots of four genotypes of C. paliurus, namely T2, W10, M31 and S12, as materials. The physiological responses of annual shoots of C. paliurus to low temperature stress were elaborated by determining and comparing indicators related to cold resistance, such as relative electric conductivity, semi-lethal low temperature, malondialdehyde, soluble sugar, soluble protein, proline, superoxide dismutase and peroxidase. The contents of malondialdehyde, proline, soluble protein and peroxidase activities were not only correlated with the treatment temperature but also related to the genotypes. Osmotic substance (soluble sugar, soluble protein and proline) contents and antioxidant enzyme activities (peroxidase and superoxide dismutase) of the four genotypes showed a trend of increasing and then decreasing with the five decreasing temperatures. Furthermore, a comprehensive evaluation of cold resistance was performed by using a combination of principal component analysis and membership function, with the cold resistance ranked as W10 > M31 > S12 > T2. Results from this study would provide some references for extending the plantation areas.

Suaeda australis is a typical halophyte due to its high salt tolerance. The WRKY gene family plays crucial roles in responding to salt stress, yet reports on WRKY genes in S. australis are scarce. In this study, we identified 47 WRKY genes in the S. australis genome. We then conducted comprehensive analyses, including investigations into their chromosomal locations, gene structures, phylogenetic relationships, promoter regions, conserved motifs, and expression profiles. The 47 WRKY genes were classified into three main groups (with six subfamilies). Among nine chromosomes, S. australis displayed an unequal pattern of distribution. The analysis of regulatory elements revealed that WRKY promoters were associated with light responsiveness, anaerobic induction, drought inducibility, meristem expression, and gibberellin responsiveness. Expression pattern analyses highlighted the role of several SaWRKYs, including Sau00527, Sau00681, Sau18413, Sau19293, Sau00810, Sau05901, Sau09209, Sau12457, and Sau14103. These genes exhibited higher expression levels under ST2 compared to ST1, indicating a significant response to salt stress. Higher SOD, POD, and CAT activity, as well as increased MDA and H₂O₂ content, were observed in ST2, in line with the expression patterns and our RTq-PCR results. Our study offers a profound understanding of the evolutionary development of S. australis WRKY members, clarifying their vital functions in responding to salt stress. Along with crucial genomic data, these findings establish a solid foundation for investigating the mechanisms of salt-stress regulation in S. australis. This research holds substantial scientific and ecological importance, offering potential contributions to the conservation of S. australis and the utilization of saline soil resources.